In recent years, an exhaust gas purifying catalyst in which noble metal particles are supported on a metal oxide carrier has been widely used in order to remove harmful substances such as hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxide (NOx) contained in exhaust gas emitted from an internal combustion engine. A conventional exhaust gas purifying catalyst contains a large amount of noble metal so as to enhance durability of noble metal particles with respect to peripheral atmospheric fluctuations. On the other hand, the use of a large amount of noble metal is not desirable in view of protection of earth resources.
In consideration of such an issue, a catalyst has been disclosed that contains transition metal such as cerium (Ce) to function as an oxygen storage component and manganese (Mn) to function as an active oxygen supplying material provided adjacent to noble metal particles by use of an impregnation method (refer to Patent Literature 1). This catalyst ensures enhanced durability of the noble metal particles due to prevention of atmospheric fluctuations at the periphery of the noble metal particles by the transition metal provided adjacent to the noble metal particles. In addition, the exhaust gas purifying catalyst manufactured by such a method is expected to have enhanced activity of the noble metal particles in addition to enhanced durability of the noble metal particles.